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Don’t ever hand your phone to the cops
(www.theverge.com)
This is a most excellent place for technology news and articles.
If you are operating a motor vehicle, you are required to hold a license to operate that vehicle. Ergo, if you are operating the vehicle, the police can ask for proof of your licensure to operate that vehicle, and you are reauired to produce it. That is not covered under search and seizure.
Then people giving this sort of practical advice should explicitly say that lest someone get arrested for failure to present a license or whatever.